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MotoLibrary Score
43/100Commuter
Power
27 HP
Top Speed
139 km/h
Torque
32 Nm
Engine
392 ccm
Technical Overview
1981 Yamaha XS 400 Special Technical Analysis & Specification Breakdown
At the heart of the 1981 Yamaha XS 400 Special classic motorcycle, Yamaha features a 392 cc (23.9 cu in) air-cooled twin, four-stroke configuration. In factory specification, peak output is rated at 27 HP (19.7 kW) at 7,500 rpm while maximum torque reaches 32.3 Nm (23.8 lb-ft) at 8,000 rpm, transferring power to the rear wheel through a 6-speed gearbox and chain final drive. With a specific output of 68.9 HP per liter, the engine character is indicating a tractable, stress-free state of tune focused on everyday usability and broad torque delivery.
On the scales, the XS 400 Special measures 180 kg (397 lbs) wet (curb), translating to a power-to-weight ratio of 0.15 HP/kg (6.67 kg per horsepower). Rider ergonomics and chassis geometry center around a 780 mm (30.7 in) seat height — offering a neutral standover height that accommodates most average-inseam riders without sacrificing cornering clearance, combined with a 1,364 mm (53.7 in) wheelbase engineered for quick, flickable steering geometry. The 14-liter (3.7 US gal) fuel tank supports practical everyday commuting and weekend road stints, while factory top speed is listed at 139 km/h (86 mph).
Specific Output
68.9 HP/L
Power-to-Weight
0.15 HP/kg (6.67 kg/HP)
Standover Height
780 mm (30.7 in)
Engine
Displacement392.0 ccm (23.92 cubic inches)
Engine TypeTwin, four-stroke
Engine DetailsTwin, four-stroke
Power27.0 HP (19.7 kW)) @ 7500 RPM
Torque32.3 Nm (3.3 kgf-m or 23.8 ft.lbs) @ 8000 RPM
Compression9.3:1
Bore x Stroke69.0 x 52.4 mm (2.7 x 2.1 inches)
Valves/Cylinder2
Fuel SystemCarburettor. Mikuni BS32
Fuel ControlOverhead Cams (OHC)
IgnitionBattery ignition with contact breaker points
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Torque
Torque is useful for judging real-world pull, especially for touring, commuting and loaded riding.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
